There is a need for a bedside monitor of cerebral hemodynamics for human patients. Near-infrared spectroscopy (NIRS) is an optically based technique that could meet such demand. Using a non-toxic near infrared dye Indocyanine green (ICG) as a tracer, cerebral blood flow (CBF) can be measured with NIRS using the Fick principle. However, NIRS based cerebral hemodynamics monitor is not yet widely used in routine clinical monitoring. One major challenge is to develop an optical probe and a corresponding algorithm to solve the problem of interference from extracerebral tissue (skin, scalp, and skull) in adult NIRS applications. Another challenge is to develop a simple accurate algorithm that will be able to quantify the arterial and cerebral ICG concentrations, which are required for CBF calculation with the Fick principle. Our goal is to resolve these challenges to develop an NIRS monitor that has an integrated probe to simultaneously measure arterial and true brain tissue ICG concentrations for quantification cerebral hemodynamics. The primary objectives of this SBIR proposal are: Design and construct a NIRS hemodynamic monitoring the system; determine the optimum integrated NIRS probe configuration to minimize extracerebral interference of brain tissue ICG concentration measurement; and evaluate feasibility of proposed algorithms and validate NIRS hemodynamics parameters in animal models. [unreadable] [unreadable]